1. Field of the Invention
The present invention relates to a pressure loss compensation device of a fluid pressure circuit in which a fluid pressure generated in a fluid pressure source is supplied to a fluid pressure actuator through piping, and a cam arrangement which incorporates the pressure loss compensation device.
2. Description of the Related Art
In general, there have been a large number of fluid pressure circuits for driving actuators employing fluid pressure. For instance, a picking and placing apparatus disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. Heisei 4-67941, employs a hydraulic circuit using a hydraulic pressure as a fluid pressure.
The picking and placing apparatus causes compound movement of an output shaft necessary for tool changing in a machine tool, by means of gears. The hydraulic circuit is employed for clamping and unclamping the tool in synchronism with rotation of an input shaft. Namely, the hydraulic circuit includes a pump device as a hydraulic pressure source generating a pulsating hydraulic pressure in synchronism with rotation of the input shaft, and an actuator, in which the hydraulic pressure generated by the pump device is introduced. The actuator is provided in a clamping device of the tool so that a rod cooperated with the actuator is projected for unclamping the tool by introducing the hydraulic pressure into the actuator.
However, in the conventional fluid pressure circuit set forth above, it is inherent to cause leakage of fluid in a structural portion of hydraulic devices per se, such as the pump device, actuator and so forth, connecting portion between the hydraulic devices and piping, through long time use. Leakage of the pressurized fluid apparently leads pressure loss to cause difficulty in supplying necessary pressure to the actuator or, in the worse case, to cause failure of operation.